GRANITE. 



75 



by piles of stones like the remains of a stratified 



mass, as in the annexed figure. 



Fig. 26. 



Granite sometimes forms veins shooting up into 

 the superincumbent rocks. This is a geological fact 

 of considerable importance, as it seems to indicate 

 either that the granite has been in a state of fusion, 

 the heat of which has softened and rent the upper 

 rocks, and forced up the granite in a melted state 

 into the fissures, or else that the granite and the 

 rock resting immediately upon it were both in a fluid 

 state at the same time, and, therefore, are contempo- 

 raneous. Professor Hitchcock, in his fleport on the 

 Geology of Massachusetts, remarks, that *' the veins 

 of granite in Massachusetts penetrate only the older 

 rocks, the clay slate being the latest in which they 

 are found. All the older stratified rocks abound in 

 them, though in quartz rock I have rarely met with 

 any. In gneiss they are very common ; in talcose 

 slate very rare ; in hornblende slate not common ; in 

 micaceous limestone sometimes met with ; in ser- 

 pentine I have never found one. In granite and sy- 

 enite they are very abundant, and almost always 

 the ingredients are much coarser than the granite 

 or syenite that contains them." "In a large major- 

 ity of cases, the intrusion of granite veins seems to 

 have produced very little disturbance in the rocks 

 containing them. They would seem to have been 

 open fissures, filled by the injection of granitic mat- 

 ter, without mateW^iii affecting the walls except to 



